In designing proper lighting for commercial and retail applications, it is necessary to consider the total space to be lighted and the specific activities that may be performed within the perspective lighted area. Normally track lighting is used with surface or recessed spotlight assemblies. In particular concern to the present invention, specialized lighting units for directing light so to spotlight and accent portions of walls and merchandise have been developed. These units, called wall wash units, serve aesthetic purposes and may also serve to highlight merchandise positioned along the walls.
Wall washing may be accomplished by flood or wide beam patterns of non-ambient or "spot" lighting. Such lighting is generally accomplished by use of incandescent filament lamps. Non-ambient lamps vary in luminosity and in heat-generation characteristics. Adding filters to the lamps will often aid in creating the desired effect.
Sometimes it is advantageous to use a combination of ambient and non-ambient or spotlighting in wall wash lighting equipment to create an attractive wall wash.
Ambient lighting can be effected in these units by incandescent or halogen lamps, fluorescent lamps, or high-intensity-discharge lamps. For commercial and retail occupations, high-intensity-discharge ("HID") lamps are preferable as they can provide a greater luminosity per watt of energy than either incandescent or fluorescent lamps. HID lamps generally require a ballast system.
As those skilled in the art will recognize, the ballast system provides circuitry and electrical components necessary for reducing the required voltage supply and for start up, reactances, and power-factor-correcting capacities. All of these electrical components are placed inside a case filled with a potting compound in the entire ballast element. The ballast element is of comparatively large size when measured against the size of the HID lamp. The ballast is usually fixed in a position relatively close to the HID lamp and obviously must be in electrical communication with the HID lamp.
Since it is necessary to replace lamps in wall units periodically, and it is desirable to periodically rearrange the lamps for aesthetic and commercial reasons, any wall wash unit should be readily accessible. Since these units are often used in retail and commercial settings where professional electricians are not available, it is desirable that the access to the wall wash unit can be undertaken by one of little working knowledge of electrical devices. Even if professional electricians are used, ease of access is important to limit the time necessary to employ the electrician. Similarly, since wall wash units are located in the ceilings of retail establishments, anyone undertaking the maintenance or rearrangement of the lights should have easy access to the units and be impeded by as few tools as possible.
Others in the past have sought to provide easy access to lighting units. For example, U.S. Pat. No. 3,883,732 to Peterson, et al. shows an illuminaire adapted for mounting in suspended ceilings which has modular construction to facilitate installation and assembly. The unit includes a rectangular open bottom housing adapted to rest on the ceiling support bars. It also includes a removable ballast supporting panel which forms a wall of the housing. U.S. Pat. No. 4,748,543 to Swarens shows a wall wash unit which does not need tools to provide access to its interior. Both require springs to hold the lamp supports in place.